Patagonia
Patagonia is a geographic region containing the southernmost portion of South America. Located in Argentina and Chile, it comprises the Andes mountains to the west and south, and plateaux and low plains to the east. The name Patagonia comes from the word patagón used by Magellan to describe the native people whom his expedition thought to be giants. It is now believed the Patagons were actually Tehuelches with an average height of 1.80 m (~5'11") compared to the 1.55 m (~5'1") average for Spaniards of the time. Geology The geological constitution is in accordance with the orographic physiognomy. The Tertiary plateau, flat on the east, gradually rising on the west, shows Upper Cretaceous caps at its base. First come Lower Cretaceous hills, raised by granite and dioritic rocks, undoubtedly of Tertiary origin, as in some cases these rocks have broken across the Tertiary beds, so rich in mammal remains; then follow, on the west, metamorphic schists of uncertain age; then quartzites appear, resting directly on the primitive granite and gneiss which form the axis of the Cordillera. Porphyritic rocks occur between the schists and the quartzites. The Tertiary deposits are greatly varied in character, and there is considerable difference of opinion concerning the succession and correlation of the beds. They are divided by Wilckensi into the following series (in ascending order): # Pyrotherium-Notostylops beds. Of terrestrial origin, containing remains of mammalia. Eocene and Oligocene. # Patagonian Molasse. Partly marine, partly terrestrial. Lower Miocene. # Santa Cruz series. Containing remains of mammals. Middle and Upper Miocene. # Paranfl series. Sandstones and conglomerates with marine fossils. Pliocene. Confined to the eastern part of the region. The Upper Cretaceous and Tertiary deposits have revealed a most interesting vertebrate fauna. This, together with the discovery of the perfect cranium of a chelonian of the genus Myolania, which may be said to be almost identical with Myolania oweni of the Pleistocene age in Queensland, forms an evident proof of the connection between the Australian and South American continents. The Patagonian Myolania belongs to the Upper Chalk, having been found associated with remains of Dinosauria. One such dinosaur to be found in Patagonia is Argentinosaurus, which may be the largest of all dinosaurs. Other specimens of the interesting fauna of Patagonia, belonging to the Middle Tertiary, are the gigantic wingless birds, exceeding in size any hitherto known, and the singular mammal Pyrotherium, also of very large dimensions. In the Tertiary marine formation a considerable number of cetaceans has been discovered. In deposits of much later date, formed when the physiognomy of the country did not differ materially from that of the present time, there have been discovered remains of pampean mammals, such as Glyptodon and Macrauchenia, and in a cave near Última Esperanza Sound, a gigantic ground sloth (Grypoiherium listai), an animal which lived contemporaneously with man, and whose skin, well preserved, showed that its extermination was undoubtedly very recent. With the remains of Grypotherium have been found those of the horse (Onoshippidium), which are known only from the lower pampas mud, and of the Arciotherium, which is found, although not in abundance, in even the most modern Pleistocene deposits in the pampas of Buenos Aires. It would not be surprising if this latter animal were still in existence, for footprints, which may be attributed to it, have been observed on the borders of the rivers Tamangoand Pista, affluents of the Las Hefas, which run through the eastern foot-hills of the Cordillera in 47°S. Category:Geography